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Old 06-26-2003, 11:00 AM
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erratic timing

at 3400 to 3600 rpm my timing starts jumping around like a flea.it jumps to 10,50,34,39,40,etc, .msd billet distributor,msd 7al,on a 466ford.msd 7al *(has no retard function ,only on7al2 ) .have replaced distributor,same thing happens.also replaced y plug,separated wires,reversed purple/yellow wires on msd box,no change. timing is solid until about 3400to 3600 rpm then madness. msd people say box cant cause that,?? has anyone experienced this?help please!thanks jimm

Last edited by jimm; 06-29-2003 at 06:32 PM.
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Old 06-27-2003, 10:09 PM
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Hi jimm, well unfortunately (or fortunately) I can't say I've had a problem similar to this traceable to a box. The only times I've seen this type of a situation (eratic timing under high rpms) is with points distributors with side to side play in the distributors shaft. Now I don't know if you remember but last year I bought a MSD distributor for my car and never even installed it. Right out of the box I was able to rock the shaft back and forth in the distributors housing. I sent it back to Summit and they sent me another one, same loseness in the shaft also. I wasn't going to pay top dollar for what I considered substandard machining. I had them send me a Mallory Unilite instead and I couldn't get the shaft in the Mallory to wobble a fraction of an inch. Now I don't know what the outcome of the loseness in the MSD distributor shafts would have been cause I never installed them but I can't see how a distributor shaft that wobbles at 4,000rpms could be any good. The only thing I can really suggest is to examine the distributors shaft real close and check for any side to side wobble. You mentioned replacing the distributor, were they both MSDs? Can you try a different distributor that's not MSD temporarily to see if it changes anything? Can you remove the box from the system to isolate it or does the distributor require a box to function? Maybe someone else has some more insight on this.


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Old 06-28-2003, 11:33 PM
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A stretched roller timing chain will do this too. Main reason why I don't care for-em for street applications.

How ya doing Jimm? Long time no see?!
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Old 06-29-2003, 07:00 PM
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dee! chuck! thanks for weighing in,yes long time,so busy finishing that blazer project you've heard so much about in the past but not seen.sorry, but a stinkin scanner costs money best spent on go fast stuff. okay, back to the problem at hand.dee, all new msd,both times.chuck, all new motor, and yes ,it is a double roller timing chain, but this snake has 8 runs on it.my brother and i are at wits end{and believe me ,it did'nt take long to get there for either of us}we just got back from the track,last vweekend 4 runs 9.089,9.065,9.038 and i dont remember the last.then this weekend 8.98,8.88,9.03{had a passenger} to refine my observations abouthe problem we tried again and this is what i saw, rock solid timing 38deg. till 4000 then it looks like shaking your hand back and forth real fast about and inch or two on the balancer. an old gentleman of much renown around here says we dont have a problem because it is not exhibiting itself in the performance of the motor,and that he has experienced this several times in his career and never solved them. sheese! i really hate problems that i cant put my finger on.will appreciate any and all input and send home made cookies to the one providing the solution!1oh yeah! guess who the passenger that slowed down the ride is? my 76 year old mom,yeeehaaaahhh!!! thanks amill guys jimm
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Old 06-29-2003, 07:10 PM
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Could it be that the problem is in the timing light itself?
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Old 06-29-2003, 07:14 PM
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How many moms get to make a 9 sec 1/4 mi pass? cool.
you said the msd people told you the box wouldn't do that..... is that the only unchanged piece in the system? i'd look there......... like the ol man said, It ain't affecting your performance........
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Old 06-29-2003, 07:33 PM
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hey larry!just for the record it was a 1000 ft. pass, but still i thought she would freak. her reply was it was nice , but it did'nt last long enough!!! haaa! oh yeah, i've tried 3 timing lights ,no change. something good to add : msd reps. have been extremely helpful and have even given us a phone no. to call up till 10pm at home. i 've gotta say that at this point i consider it an anomaly {cool word, but what the hair does it mean?} and plan to race as is . should the solution /cause come to light i will make haste to let you guys know. many thanks to the coolest site and the coolest guys,jimm
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Old 06-29-2003, 07:36 PM
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Hi again jimm! I know it may be a pain but is there any way you could borrow another distributor (non MSD) to stick in her just to see how she handles rpms. I say this only because I saw firsthand what I considered to be simply substandard machining in two MSD distributors. Before I put the Unilite in my Mustang I was having trouble with intermittantly breaking up and stalling. I was pretty sure it was the distributor but before I spent big money (since the problem was intermittant) I actually dropped an old stock single-point distributor in her just to see what would happen. After running trouble free for a week I ordered my new parts. No problems since.

May be a stretch here but is the #1 plug wire close to the other wires where the inductive pick-up is? Could it be picking up interference from another wire at high rpms? Just thinkin' out loud here.:drool

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Old 07-07-2003, 07:23 PM
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Cool

hey guys, just trying to tie up loose ends here.inn reply to the timing light broken proposal by bestmech {i think?} no dice ! , we tried 4 diff. ,same results. so ! heres the deal, got a msd crank trigger , all is well,,,, well not really. what i mean is the crank trigger fixed the erratic timing ,but when we ran sunday the genie punched out and long faces are abundant round here! autopsy tonight ,but prelim looks like rod let go. oh yeah ! next to last run was 8.77 so it looks like improved timing was good for about six hundreths or so. will cry on any and all shoulders,the block is holed!!!@@##$%$^%^&*()*&% amen goodnight,jimm
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Old 07-08-2003, 10:32 AM
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hey jimm, really sorry to hear about the last run. My question to you is is it possable the rod was your problem all along?? I really thought it was the distributor, I'v had the loose shaft problem too. One time the distributor cap wasn't secure. And the timing chain, but the problem started at lower RPMs. Good luck on the new build up!!


Todd??
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Old 07-26-2003, 06:00 PM
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hey guys! guess what ? it wasnt the rod it was the stinkin valve spring cap,,,broke in half!!!!!!!!!!!!!!! thennnnn,,, guess what happened next?yup! the bad part is that the heads were brand spankin new edelbrock alum, fully assembled,about two gees and change.the good part is that edelbrock is currently working on a compensation package. talk about stand up folks.anyway,just wanted to let you all know the rest of the story
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Old 07-26-2003, 10:56 PM
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Lightbulb erratic timing answer

Jimm,

Sounds like a fun ride. Alittle too much maintenance for me, but plenty of fun. I was doing some ignition research, and I came across your post. It seems I have come along alittle too late in the game. I know what causes your erratic timing, but it usually appears when motor's on the way out or loose. It can be anything that causes the cam to vary from the crank. Most of the time, it is a wore out timing chain and appears in a wider range of rpms. This problem can also be related to sticky lifters(hydraulic), rockers, or valves. With the rise in rpms, the timing chain becomes more stressed. Any little variation will cause the timing to bump around. Most times it is unnoticeable, especially in a balanced and blueprinted engine. On the daily drivers, it signifies a loose engine. On performance engines, it signifies a problem that should be attended to promptly. Unfortunately, that means a partial teardown, and some close (professional) inspection. It is unlikely you will ever come across the problem again, but if you do, now you know what to do.
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